(1) Field of the Invention
This invention relates to disposal of acid gases. Acid gas as used herein is defined as a gaseous mixture of varying concentrations of carbon dioxide (CO2) and hydrogen sulfide (H2S) resulting from treating processes employed to remove these contaminants from sour hydrocarbon streams such as produced natural gas. These mixtures often are water saturated and contain small amounts of hydrocarbons, treating solvents, absorbants, and other matter.
(2) Description of the Related Art
Before this invention, BEARD in U.S. Pat. No. 5,340,382 disclosed the process of absorbing acid gas at about 400 psi into produced water by a static mixing unit and then pumping the solution into a disposal well. The BEARD process uses about 160 barrels water for about 1,000 cu. ft. of acid gas. If the acid gas were liquified, this would be a ratio (by volume) of approximately 424 H2O:1 dense fluid acid gas.
In Canada (where the acid gases have high hydrogen sulfide content) acid gas is dehydrated, compressed, and injected into disposal wells. Reports of such are found in the Oil & Gas Journal of Apr. 18, 1997 by Edward Wichert and Tom Royan; the 1996 paper given by H. L. Longworth, G. C. Dunn and M. Semchuck at the gas and technology conference held in Calgary, Alberta from the 28th of April until May 1, 1996; the paper of Wichert and Royan given at the same meeting in 1996.
Sulfur recovery plants are another method of dealing with acid gas. This process utilizes catalyst beds to convert over 99% of the H2S to elemental sulfur. The process off gas is incinerated resulting in release of associated carbon and sulfur dioxides as emissions to the atmosphere.